Thank you for fine folks at OSX Daily for saving my beacon. This article has been really helpful in sorting out my friend’s iMac.
Intel Mac Startup Key Combos
To use one of these startup key combinations on the Mac, start holding down the key immediately upon boot or reboot, basically right after you hear the system chime you want to begin holding down the key to achieve it’s desired effect.
Keystroke | Description |
Press C during startup | Start up from a bootable CD or DVD, such as the Mac OS X Install disc that came with the computer. |
Press D during startup | Start up in Apple Hardware Test (AHT), if the Install DVD 1 is in the computer. |
Press Option-Command-P-R until you hear two beeps. | Reset NVRAM |
Press Option during startup | Starts into Startup Manager, where you can select a Mac OS X volume to start from. Note: Press N to make the the first bootable Network volume appear as well. |
Press Eject, F12, or hold the mouse (/trackpad) button | Ejects any removable media, such as an optical disc. |
Press N during startup | Attempt to start up from a compatible network server (NetBoot). |
Press T during startup | Start up in FireWire Target Disk mode. |
Press Shift during startup | Start up in Safe Boot mode and temporarily disable login items. |
Press Command-V during startup | Start up in Verbose mode. |
Press Command-S during startup | Start up in Single-User mode. |
Press Option-N during startup | Start from a NetBoot server using the default boot image. |
Note that newer Macs running Lion or later will also the ability to boot into Recovery Mode by holding down Command+R during startup.
via 11 Startup Key Combinations for Intel Macs